Karlsson was born near Malmö in 1973 and began playing guitar at eight. After hearing Iron Maiden's 1983 classic Piece of Mind, the youngster devoted himself to the guitar, eventually adding classical, jazz, and folk to his studies as a way of nurturing his chosen role as a metal guitarist. After working his way through a master's degree from Malmö College of Music, he formed melodic death metal band Ablaze My Sorrow and released If Emotions Still Burn in 1995 and The Plague in 1998. Last Tribe signed with Italian hard rock label Frontiers Records. After three well-received, charting full-lengths -- 2001's The Ritual, 2002's Witch Dance, and 2003's The Uncrowned -- the group disbanded. That same year he issued Anger, Hate and Fury with Ablaze My Sorrow.
Karlsson committed himself to a number of different collaborative projects. He wrote, did session work and formed several bands for Frontiers including Allen/Lande -- whose The Battle appeared in 2005, Bob Catley, and Kiske/Somerville. Karlsson also founded power metal outfit Starbreaker in 2005 and issued their self-titled debut to global acclaim. After playing a couple of solos on 2007's New Religion, legacy German metal outfit Primal Fear asked him to join the band full-time. He did and remains a core part of their lineup.
Starbreaker issued its sophomore outing, Love's Dying Wish in 2008 followed by European tour. Primal Fear released 16.6 Before the Devil Knows You're Dead in 2009, and toured the globe, resulting in 2010's Live in the USA. Though Karlsson was busy with Primal Fear, he made time to collaborate with Allen-Lande on The Showdown during tour breaks. In 2011 he was recruited as a session guitarist by veteran German metal band Sinner, and appeared on their studio outing, One Bullet Left.
By 2013, Karlsson enjoyed a sterling reputation as a conceptualist as well as a guitarist, composer, and producer. He formed Magnus Karlsson's Free Fall as a one-man band project with guest singers, Karlsson played all instruments save for drums; he wrote and arranged the material and produced the sessions. HIs singers included Russell Allen (Allen-Lande, Symphony X, Adrenaline Mob), Tony Harnell (TNT, Starbreaker), Mark Boals (Yngwie Malmsteen, the Codex), and more. While the album drew positive critical notice in the Americas, it landed in the upper rungs of the charts in several European countries. Magnus Karlsson's Free Fall issued the follow-up album, Kingdom of Rock in 2015, utilizing a more diverse cast of singers including Jorn Lande, Rebecca De La Motte, Joe Lynn Turner, David Readman and Jakob Samuel.
After recording 2016's Rulebreaker with Primal Fear and going on tour, Karlsson reconvened Ablaze My Sorrow to release Black. ?He also assisted Sinner on 2017's Tequila Suicide. That same year Karlsson formed the Ferrymen with American drummer Mike Terrana and vocalist Ronnie Romero. Their self-titled debut arrived to chart success at streaming before year's end. The following year, Primal Fear claimed almost all of Karlsson's time. They released two albums -- Apocalypse and Crucify Me -- and toured the world.
2019 saw the release of the Ferrymen's acclaimed sophomore outing, A New Evil, and Starbreaker's third album, Dysphoria. Somehow, Karlsson also found time to play on Sinner's Santa Muerte. The guitarist resumed work with Primal Fear in 2020, recording and touring behind the album Metal Commando. He also wrote material for We Are the Night, a dramatic 12-song set that brought back some of the same singers and included newcomers Dino Jelusic (Trans-Siberian Orchestra), Noora Louhimo (Battle Beast) and Brazilian vocalist Renan Zonta. He also worked on Allen-Olzon's Worlds Apart (with ex-Nightwish and current the Dark Element vocalist Anette Olzon, who replaced Jorn Lande).
Karlsson didn't slow down in 2021. Primal Fear issued I Will Be Gone EP for Nuclear Blast, and began making plans to tour the world the following year. The guitarist also assembled and recorded two new projects. He formed Heart Healer to release the conceptual The Metal Opera by Magnus Karlsson. The ensemble was conceived by the guitarist with Frontiers label boss Serafino Perugino, and featured a heavy metal quartet with symphonic orchestration framing seven operatic female metal singers including Adrienne Cowan (Seven Spires, Avantasia), Netta Laurenne (Smackbound, Laurenne/Louhimo), Youmna Jreissati (Ostura), Ailyn (Her Chariot Awaits, ex-Sirenia), Noora Louhimo Margarita Monet (Edge of Paradise), and Anette Olzon. Karlsson also reunited with Ablaze My Sorrow after a five-year break and released the studio outing Among Ashes and Monoliths. ~ Tim Monger & Thom Jurek, Rovi